As is known, an electro-optic modulator having a plurality of individually addressable electrodes may be employed as a multigate light valve for line printing. See, for example, U.S. Pat. No. 4,281,904 which issued Aug. 4, 1981 on an application of R. A. Sprague et al., for a "TIR Electro-Optic Modulator with Individually Addressable Electrodes". Also see, "Light Gates Give Data Recorder Improved Hardcopy Resolution," Electronic Design, July 19, 1979, pp. 31-32; "Polarizing Filters Plot Analog Waveforms," Machine Design, Vol. 51, No. 17, July 26, 1979, p. 62; and "Data Recorder Eliminates Problem of Linearity," Design News, Feb. 4, 1980, pp. 56-57.
Substantial progress has been made in developing multigate light valves of the foregoing type and in applying them to electro-optic line printing. A commonly assigned U.S. Pat. No. 4,389,659 of R. A. Sprague, which issued June 21, 1983 on an "Electro-Optic Line Printer," shows that an image represented by a serial input data stream may be printed on a standard photosensitive recording medium through the use of a multigate light valve that is illuminated by a more or less conventional light source. That disclosure is of interest primarily because it teaches input data sample and hold techniques for increasing the exposure contrast. Another commonly assigned U.S. Pat. No. 4,396,252 of W. D. Turner, which issued Aug. 2, 1983 on "Proximity Coupled Electro-Optic Devices," teaches that the electrodes and the electro-optic element of a multigate light valve may be physically distinct components which are pressed or otherwise firmly held together to achieve "proximity coupling." Still another commonly assigned U.S. Pat. No. 4,367,925 of R. A. Sprague et al., which issued Jan. 11, 1983 on "Integrated Electronics for Proximity Coupled Electro-Optic Devices," shows that it is relatively easy to make the necessary electrical connections to the many electrodes of a typical proximity coupled multigate light valve if the electrodes are formed by suitably patterning a metallization layer of, say, a VLSI silicon electrode driver circuit. A further copending and commonly assigned U.S. patent application of W. D. Turner et al., which was filed Sept. 17, 1980 under Ser. No. 187,916 on "Differential Encoding for Fringe Field Responsive Electro-Optic Line Printers," teaches that the number of electrodes required of a multigate light valve to obtain a given resolution from an electro-optic line printer is reduced by a factor of two if the input data is differently encoded. Another commonly assigned U.S. Pat. No. 4,415,915 of R. A. Sprague et al., which issued Nov. 15, 1983 on "Multilayer Interleaved Electrodes for Multigate Light Valves," shows that increased electro-optic efficiency and improved resolution may be obtained from a multi-gate light valve by using two or more layers of interleaved electrodes. Yet another commonly assigned U.S. Pat. No. 4,413,270 of R. A. Sprague, which issued Nov. 1, 1983 on "Multigate Light Valve for Electro-optic Line Printers Having Non-Telecentric Imaging Systems," describes a converging electrode geometry which simplifies the imaging optics that are required to apply such a light valve to electro-optic line printing or the like. Furthermore, another copending and commonly assigned U.S. patent application of R. A. Sprague on "Non-Uniformity Compensation For Multigate Light Valves" provides a technique for reducing data independent variations in the optical output of a multigate light valve. And still another commonly assigned U.S. Pat. No. 4,437,106 of R. A. Sprague which issued Mar. 13, 1984 on "Method and Means for Reducing Illumination Nulls in Electro-Optic Line Printers" describes approaches that may be taken to minimize the interpixel illumination nulls that electro-optic line printers characteristically exhibit.
It has also been shown that an electro-optic element having individually addressable electrodes may be used as a beam deflector to scan or otherwise move a light beam across an image plane. See a commonly assigned U.S. Pat. No. 4,386,827 of D. R. Scifres et al, which issued June 7, 1983 issued June 7, 1983 on an "Electrooptical Scanning Device".
As a general rule, prior electro-optic light valves and beam deflectors have been configured to spatially modulate a light beam along a single transverse axis. This has limited their utility. For example, prior electro-optic line printers have normally required a relatively intense light source, such as a laser, to print at an acceptable rate. Similarly, prior electro-optic beam deflectors have been able to control the lateral position of the deflected beam, but not its longitudinal position.